Polymethylsesquioxane powders are described in U.S. Pat. No. 4,528,390 to Kimura in which the powders are prepared by hydrolytic condensation of methyltrimethoxysilane in an ammoniacal medium with subsequent washing and drying of the precipitate.
Nugent describes in U.S. Pat. No. 3,383,773 a process for preparing reproducible solid powdered solvent-soluble prepolymers of organopolysiloxanes which are prepared by hydrolytic condensation of methyltrialkoxysilanes and phenyltrialkoxysilanes. In this process, the organopolysiloxanes are dissolved in methylene chloride and spray-dried.
Therefore, it is an object of the present invention to provide silicone resin powders having a particle size in the range of from 1 to 100 .mu.m, and having a large available surface area with narrow grain-size distribution. Another object of the invention is to provide silicone resin powders having good flow properties, and whose chemical composition and functionality of the siloxane units can be varied. Still another object of the invention is to provide a process for preparing finely divided silicone resin powders without using complex mechanical grinding equipment and without sorting or filtration steps. A further object of the present invention is to provide a process for preparing finely divided silicone resin powders which are reproducible from batch to batch.